The proposed research is directed toward understanding the effect of the physiological environment on the degradation of polymeric biomaterials. Accelerated in vivo and in vitro methods will be used to study biodegradation of polyurethane elastomers used in cardiovascular applications. Procedures for an accelerated in vivo biodegradation test will be developed using chemotactic peptides. Temporal variations of enzyme levels and inflammatory cells in the exudate will be correlated with observed property changes. A model poly(alpha-amino acid) elastomer will be used to gain a fundamental understanding of the enzyme degradation mechanism. Stress-enhancement is proposed as a new method of accelerated in vitro testing. This method is also relevant to many end use applications of the materials chosen for investigation.